1. Field of the Invention
The invention relates to a liquid crystal display device, and more particularly, to an apparatus for correctly inspecting rubbing inferiority of an alignment film after the alignment film is formed.
2. Description of the Related Art
Various portable electric devices such as mobile phones, personal digital assistants (PDA), and notebook computers have recently been developed. Therefore, the need for a flat panel displays used in small, light weight, power- efficient and portable devices has correspondingly increased. To meet this need, flat panel display device technologies such as liquid crystal display (LCD) technology, plasma display panel (PDP) technology, field emission display (FED) technology, and vacuum fluorescent display (VFD) technology have been actively researched. Of these flat panel display devices, the LCD is preferred due to current mass production, efficient driving schemes, and superior image quality.
FIG. 1 is a schematic view showing a sectional surface of a general LCD device in accordance with the related art. As shown in FIG. 1, the LCD 1 contains a lower substrate 5, an upper substrate 3, and a liquid crystal layer 7 formed between the lower substrate 5 and the upper substrate 3. The lower substrate 5 and the upper substrate 3 are separated by a spacer 9. The lower substrate 5 is a driving device array substrate. Multiple of pixels (not shown) are formed on the lower substrate 5, and a driving device such as a thin film transistor (TFT) is formed on each pixel. The upper substrate 3 can be a color filter substrate, and a color filter layer for realizing color is formed thereon. Further, a pixel electrode and a common electrode are formed on the lower substrate 5 and the upper substrate 3, respectively. An alignment film 6 is formed on the lower substrate 5 and the upper substrate 3 to align liquid crystal molecules of the liquid crystal layer 7 uniformly.
Liquid crystal molecules are arranged on the alignment film 6 along a direction of grooves formed through a rubbing process, and an initial alignment direction and a pretilt angle of the liquid crystal molecules are determined by the rubbing process.
Generally, a rubbing inferiority inspection using moisture is performed after an alignment film rubbing process.
FIG. 2 is an apparatus for inspecting rubbing inferiority of an alignment film of a liquid crystal display device in accordance with the related art. As shown, the related rubbing inferiority inspection was performed by spraying minute moisture particles 17 on an alignment film 14 formed on a substrate 15, followed by checking the stain of the moisture 17 sprayed on the alignment film 14.
The moisture particles 17, i.e., aerosol, are sprayed on the substrate 15 through a pipe 13, and the minute moisture particles 17 are generated from a separately provided alignment film rubbing inferiority inspecting apparatus 10.
The alignment film rubbing inferiority inspecting apparatus 10 includes moisture storing unit 11 and a moisture particle generating unit 12 for pelletizing, i.e., aerosolizing, moisture ejected from the moisture storing unit 11, and then spraying on the substrate 15 through the pipe 13. Although not shown, the moisture particle generating unit 12 includes a heater for heating moisture, and a filter through which vaporized moisture passes. Moisture particles are formed by passing through the filter, and the moisture particles are ejected out of the pipe using N2 to thus be sprayed on the substrate.
However, in the conventional alignment film rubbing inferiority inspecting apparatus 10, since a length of the pipe 13 through which the moisture particles pass is long, the moisture particles agglomerate while passing through the pipe. Accordingly, even if uniform moisture particles are generated from the moisture particle generating unit 12, the size of the moisture particles 17 substantially sprayed on the substrate 15 is not uniform, thereby causing difficulty in correctly inspecting for rubbing inferiority.
Since the moisture particle generating unit 12 also requires the heater, the filter, etc., the alignment film rubbing inferiority inspecting apparatus has a voluminous space.